Travis: smaller changes

- add MRI 2.5
- align with config from influxdb Rubygem

.travis.yml

@@ -4,7 +4,9 @@ language: ruby
 before_install:
   - gem update --system --no-doc
   - gem install bundler --no-doc
+  - gem update bundler --no-doc
 rvm:
+  - 2.5.0
   - 2.4.2
   - 2.3.5
   - 2.2.8
@@ -17,17 +19,19 @@ gemfile:
 matrix:
   exclude:
     # Rails 5+ only on MRI 2.3+
-    - { rvm: "2.2.8",   gemfile: "gemfiles/Gemfile.rails-5.1.x" }
-    - { rvm: "2.2.8",   gemfile: "gemfiles/Gemfile.rails-5.0.x" }
+    - { rvm: "2.2.8", gemfile: "gemfiles/Gemfile.rails-5.1.x" }
+    - { rvm: "2.2.8", gemfile: "gemfiles/Gemfile.rails-5.0.x" }
 
     # Rails < 5 not on MRI 2.4
     - { rvm: "2.4.2", gemfile: "gemfiles/Gemfile.rails-4.2.x" }
     - { rvm: "2.4.2", gemfile: "gemfiles/Gemfile.rails-4.1.x" }
     - { rvm: "2.4.2", gemfile: "gemfiles/Gemfile.rails-4.0.x" }
-
-notifications:
-  email:
-    - pilots@errplane.com
-  on_success: change
-  on_failure: always
+    - { rvm: "2.5.0", gemfile: "gemfiles/Gemfile.rails-4.2.x" }
+    - { rvm: "2.5.0", gemfile: "gemfiles/Gemfile.rails-4.1.x" }
+    - { rvm: "2.5.0", gemfile: "gemfiles/Gemfile.rails-4.0.x" }
+addons:
+  apt:
+    packages:
+      - haveged
+      - libgmp-dev
 script: bundle exec rake spec